Poop, dead bugs & plant matter, and runoff don't contaminate drippers or misters.
Do you drink water from your toilet bowl, bathtub, and /or gutters?
Then by all means, use a desktop waterfall/fountain for ambience
outside the enclosure.
That's not really a concern. Chameleons can properly hunt & find food practically from the moment they hatch.
With so many live plant and vine options, why use fake at all,
especially with a baby? You have
more than enough time for real vines to grow with her (which I don't think is really necessary either; my panther climbs all around everything—even thin stems & twigs you wouldn't think could/would support his weight—with no problems).
‽‽‽ Like the fountain, I don't understand the rocks. While not a common/frequent event, chameleons can & do fall. IMO, this is inviting catastrophe.